Electrocardiography is the well-established, but still rapidly developing, science of making and studying graphic records (electrocardiograms) generated by electrical currents originating in an animal heart, most often a mammalian heart.
An electrocardiogram (ECG) is measured through utilization of an electrocardiograph instrument, which monitors the electric potentials associated with those electric currents that transverse the heart.
In practice, electrodes are positioned on the skin surface of the subject to be evaluated. Those electrodes are in electrical communication with the electrocardiograph instrumentation. The electrodes must generally be such as can accurately detect and transmit electrical signals produced by various biological events.
An acceptable biomedical electrode has an adequate conductive surface for receipt of electrical signals from the body, a good conductive interface between the electrical instrumentation and the subject, and sufficient adherence of the electrode during the period of evaluation.
Electrocardiography has been applied in a variety of circumstances including: in resting diagnostic procedures; in surgical and emergency room procedures; in cardiac units; in critical care units; in ambulatory monitoring; in stress diagnostic procedures; and in more continual, or intermittent, monitoring as selected for a person not under constant supervision and not substantially restrained with respect to activity.
Thus, the period of evaluation and the condition of evaluation environment can differ among the various types of ECG procedures.
Regardless of the period of evaluation or condition of evaluation environment, an acceptable biomedical electrode must perform adequately to be a useful evaluation component: adequate conductive surface, good conductive interface, and continued skin adherence during the period of evaluation.
Another factor in the acceptability of a biomedical electrode is cost. Due to hygiene and other expense of re-use considerations, many biomedical electrodes are designed to be disposable after a single use. Biomedical electrodes used during limited periods of evaluation, such as resting, emergency, or surgical diagnosis, can be constructed and priced for a single use before disposal.
Biomedical electrodes have been known to provide an electrically conductive tab extending beyond the perimeter of the conductive surface area of the biomedical electrode. Examples of biomedical electrodes of this type are disclosed in U.S. Pat. No. 4,539,996 (Engel), U.S. Pat. No. 4,543,958 (Cartmell), U.S. Pat. No. 4,694,835 (Strand), and U.S. Pat. No. 4,852,571 (Gadsby et al.). An electrically conductive tab extending beyond the perimeter of the conductive surface area of the biomedical electrode requires mechanical and electrical contact in an area adjacent to skin of a subject.
Other biomedical electrodes provide an electrically conductive tab within the perimeter of the conductive surface area of the biomedical electrode by having the tab emerge from a skin contacting side of the electrode through a slit or seam in the outer protective layer of the electrode. Examples of biomedical electrodes of this type are disclosed in U.S. Pat. No. 1,622,446 (Wappler), U.S. Pat. No. 4,166,465 (Esty), U.S. Pat. No. 4,852,571 (Gadsby et al.), European Publication 0 360 496 (Strand et al.), and British Patent Specification 1 519 782 (Osborn et al.). Production of electrodes of this type require elaborate manufacturing techniques to make a slit or form a seam, with the tab extending therethrough.
Still other biomedical electrodes provide an electrically conductive tab within the perimeter of the conductive surface area of the biomedical electrode by having the outermost protective layer cut along a line within the perimeter of protective layer to form a tab from the protective layer. Examples of biomedical electrodes of this type are disclosed in U.S. Pat. No. 4,657,023 (Kuhn), U.S. Pat. No. 4,679,563 (Wada et al.), and U.S Pat. No. 4,922,911 (Wada et al.). Production of electrodes of this type also require elaborate manufacturing techniques to make a cut in the outermost protective layer and creating an electrically conductive tab therefrom which can be lifted from the remainder of the protective layer for use.